Fabrication and electrical conductivity regulation of CNTs-MoB₂-SiHfBCN ceramic films

The thin-film electrode, as the core unit of wireless passive surface acoustic wave sensors, undertakes the signal conversion function. However, finding materials for thin-film electrodes that endure high temperatures while retaining excellent conductivity remains a formidable challenge. In this research, a series of SiHfBCN-based films doped with different fillers were fabricated via the polymer-derived ceramic method. Subsequently, the effect of film microstructure on room- and high-temperature conductivity was studied. Results showed the sole MoB₂-doped film demonstrated the best electrical conductivity at room temperature. In contrast, adding CNTs lowered film conductivity due to filler agglomeration. Nevertheless, higher film pyrolysis temperatures built better conductive networks. At high temperatures, SiHfBCN-based films exhibited much lower resistivity compared to room temperature, with a minimum of 0.1 Ω cm. Moreover, after the high-temperature test, the films still retained a dense surface morphology. These findings strongly suggest SiHfBCN-based films have great promise and application potential for high-temperature electrodes.